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 \begin{table}[htpb!]
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\caption{\textbf{Effect of maternal health on twinning (unstandardised   variables)} \footnotesize{ Results from OLS regressions of a child's     birth type (twin or singleton) on the mother's health behaviours and      conditions are displayed. Specifications are identical to those in table 1,however each independent variable is unstandardised, so all coefficients   are interpreted as the effect of a 1 unit increase in the independent      variable. For indicators like smoking this is a switch from not smoking to smoking. Asterisks indicate significance levels of p-values, with: *p$<$0.1**p$<$0.05  ***p$<$0.01. 95\% confidence intervals are displayed in        parentheses. Further details regarding estimation samples and variable     construction are available in Methods.}}
\scalebox{0.90}{\begin{tabular}{llcllc}
 \toprule\multicolumn{3}{c}{Health Behaviours / Access} &\multicolumn{3}{c}{Health Conditions } \\ 
\cmidrule(r){1-3} \cmidrule(r){4-6} 
Variable & Estimate & [95\% CI] &Variable & Estimate & [95\% CI]\\ \midrule 
\rowcolor{LightCyan} \multicolumn{6}{c}{\textbf{Panel A: United States}} \\ 
Smoked Before Pregnancy&-0.325$^{***}$&[-0.409,-0.241]&Height&0.086$^{***}$&[0.082,0.090]\\
Smoked Trimester 1&-0.724$^{***}$&[-0.818,-0.630]&Underweight&-0.644$^{***}$&[-0.750,-0.538]\\
Smoked Trimester 2&-0.936$^{***}$&[-1.036,-0.836]&Obese&0.088$^{**}$&[0.017,0.159]\\
Smoked Trimester 3&-0.969$^{***}$&[-1.069,-0.869]&Diabetes&-3.365$^{***}$&[-3.718,-3.012]\\
Education&0.447$^{***}$&[0.429,0.465]&Hypertension&-1.857$^{***}$&[-2.141,-1.573]\\
\rowcolor{LightCyan} \multicolumn{6}{c}{\textbf{Panel B: Sweden}} \\ 
Smoked (12 weeks)&-0.704$^{***}$&[-0.798,-0.610]&Height&0.099$^{***}$&[0.095,0.103]\\
Smoked (30-32 weeks)&-1.030$^{***}$&[-1.132,-0.928]&Underweight&-0.716$^{***}$&[-0.887,-0.545]\\
&&&Obese&-0.411$^{***}$&[-0.497,-0.325]\\
&&&Asthma&-0.085&[-0.189,0.019]\\
&&&Diabetes&-3.737$^{***}$&[-4.113,-3.361]\\
&&&Kidney Disease&-1.359$^{***}$&[-1.731,-0.987]\\
&&&Hypertension&-1.872$^{***}$&[-2.286,-1.458]\\
\rowcolor{LightCyan} \multicolumn{6}{c}{\textbf{Panel C: United Kingdom (Avon)}} \\ 
Healthy Foods&1.333$^{***}$&[0.635,2.031]&Height&0.059$^{***}$&[0.016,0.102]\\
Fresh Fruit&0.039&[-0.594,0.672]&Underweight&-0.794&[-2.164,0.576]\\
Alcohol (Infrequently)&-0.259&[-0.976,0.458]&Obese&-0.218&[-1.512,1.076]\\
Alcohol (Frequently)&-1.567$^{***}$&[-2.759,-0.375]&Diabetes&-0.951&[-5.573,3.671]\\
Passive Smoke&0.096&[-0.494,0.686]&Hypertension&-2.536$^{***}$&[-3.975,-1.097]\\
Smoked during Pregnancy&-0.433&[-1.199,0.333]&&&\\
Education&0.225$^{*}$&[0.000,0.450]&&&\\
\rowcolor{LightCyan} \multicolumn{6}{c}{\textbf{Panel D: Chile}} \\ 
Smoked during Pregnancy&-1.089$^{***}$&[-1.879,-0.299]&Underweight&-0.821$^{*}$&[-1.680,0.038]\\
Drugs (Infrequently)&-0.079&[-3.374,3.216]&Obese&-1.813$^{***}$&[-2.991,-0.635]\\
Drugs (Frequently)&-3.098$^{***}$&[-3.741,-2.455]&&&\\
Alcohol (Infrequently)&-0.375&[-1.437,0.687]&&&\\
Alcohol (Frequently)&-2.779$^{***}$&[-3.412,-2.146]&&&\\
Education&0.123$^{***}$&[0.039,0.207]&&&\\
\rowcolor{LightCyan} \multicolumn{6}{c}{\textbf{Panel D: Developing Countries}} \\ 
Doctor Availability&0.321$^{***}$&[0.203,0.439]&Height&0.040$^{***}$&[0.036,0.044]\\
Nurse Availability&0.253$^{***}$&[0.130,0.376]&Underweight&-0.288$^{***}$&[-0.366,-0.210]\\
Prenatal Care Availability&0.549$^{***}$&[0.410,0.688]&Obese&0.196$^{***}$&[0.098,0.294]\\
Education&0.033$^{***}$&[0.025,0.041]&&&\\
\bottomrule 
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